PROJECT SUMMAY / ABSTRACT Human immunodeficiency virus (HIV) significantly burdens youth 13?17 years of age in the United States (US). Adolescents also have high rates of other sexually transmitted infections (STIs), which increases risk of HIV acquisition and transmission. Sexual, gender, and racial/ethnic minority adolescents are disproportionately affected. Increasing HIV/STI testing and pre-exposure prophylaxis (PrEP) use are key components of the US national strategy to decrease HIV rates among adolescents. Despite this, few adolescents have received HIV/STI testing or PrEP. Confidentiality concerns are a significant barrier to HIV/STI testing and PrEP use among adolescents. To allay these concerns, many states have enacted statutes permitting minors to waive guardian consent for HIV/STI testing, treatment, and prevention services, including PrEP. Although these laws are meant to protect youth from unwanted disclosure to their guardians?and thereby increase uptake of HIV/STI testing and PrEP?there is a dearth of research assessing how these laws relate to behavior and whether youth are aware of these laws. Our proposed study addresses this gap through pursuing three aims. First, to assess longitudinal changes in minor consent laws for HIV/STI testing, treatment, and prevention from 1985?present, legal experts on our team will conduct the first-ever longitudinal content analysis of state minor consent laws. A longitudinal dataset specifying and quantifying changes in the laws over time and by state will be created and made publicly available. Second, we will longitudinally evaluate the effect of changes in minor consent laws on HIV/STI testing and treatment among adolescents. To do this we will link the longitudinal legal dataset created in the first aim to adolescent health behavior data in the National Survey of Family Growth. Using a difference-in-difference-in-differences approach, we will evaluate whether changes in minor consent laws were associated with changes in HIV/STI testing and treatment for youth overall and by sex, race/ethnicity and sexual minority status. Third, we will assess relations between current knowledge and perceptions of minor consent laws, HIV/STI testing, and PrEP uptake among adolescents via a cross-sectional online survey of adolescents (N = 6120, ages 13-17 years) from all 50 states and the District of Columbia. The survey will examine: (1) knowledge and perceptions of current minor consent laws; (2) HIV/STI testing and PrEP knowledge and uptake; and (3) best practices for disseminating this information to youth. Analyses will be conducted for youth overall and by sex, gender, race/ethnicity and sexual minority status. This study will (1) provide the most comprehensive, methodologically rigorous evaluation of minor consent legislation to date; (2) identify for the first time how these statutory protections affect testing and treatment over time; and (3) identify awareness and comprehension of these laws, as well as potential barriers that continue to impede HIV/STI testing and PrEP access among adolescents.